Bearing and expansion joint system including same

ABSTRACT

A bearing is provided for use in connection with expansion joint systems. The structure of the bearing permits improved motion of, and provides improved support for, the components of the expansion joint system that are supported on or engaged with the bearing. The bearing is particularly useful for expansion joint systems in roadway constructions, bridge constructions, and architectural structures.

BACKGROUND

The present invention relates to a bearing structure. The presentinvention more particularly relates to a bearing structure for anexpansion joint system and an expansion joint system including thebearing structure.

An opening or gap is purposely provided between adjacent concretestructures for accommodating dimensional changes within the gapoccurring as expansion and contraction due to temperature changes,shortening and creep of the concrete caused by prestressing, seismiccycling and vibration, deflections caused by live loads, andlongitudinal forces caused by vehicular traffic. An expansion jointsystem is conventionally utilized to accommodate these movements in thevicinity of the gap.

Bridge constructions are also subject to relative movement in responseto occurrence of thermal changes, seismic events, and vehicle loads.This raises particular problems, because the movements occurring duringsuch events are not predictable either with respect to the magnitude ofthe movements or with respect to the direction of the movements. Gaps oropenings in the bridge deck are provided for accommodating thesemovements, and expansion joint systems are often installed in the gap.In many instances, bridges have become unusable for significant periodsof time, due to the fact that traffic cannot travel across damagedexpansion joints.

Prior art expansion joint systems include various types of bearings forabsorbing loads applied to the expansion joint system and for supportingthe various expansion joint system components. However, many of thebearings used in expansion joint systems cannot absorb the increasedloads and rotations that are demanded by the roadway and bridge designs.Therefore, a need still exists in the art for an improved bearingstructure that can accommodate increased loads and an expansion jointsystem including an improved bearing that can accommodate movements thatoccur in the vicinity of a gap having an expansion joint between twoadjacent roadway sections, for example, movements that occur inlongitudinal and transverse directions relative to the flow of traffic,and which are a result of thermal changes, seismic events, anddeflections caused by vehicular loads.

SUMMARY

A bearing structure is provided, said bearing structure comprising abearing substrate and an upper bearing portion disposed on a portion ofsaid bearing substrate, said upper bearing portion including concavelycurved side walls.

According to certain embodiments, the upper bearing portion includescurved side walls, a substantially curved upper bearing surface, and aflat seat region.

An expansion joint system is further provided for a roadway constructionwherein a gap is defined between adjacent first and second roadwaysections, said expansion joint system extending across said gap topermit vehicular traffic, said expansion joint system comprisingtransversely extending, spaced-apart, vehicular load bearing members,elongated support members having opposite ends positioned below saidtransversely extending load bearing members and extending longitudinallyacross said expansion joint gap, first means for accepting ends of saidlongitudinally extending elongated support members for controlling themovement of said ends of said support members within said first meansfor accepting longitudinally extending elongated support members, secondmeans for accepting opposite ends of said longitudinally extendingelongated support members for controlling the movement of said oppositeends of said support members within said second means for acceptinglongitudinally extending elongated support members, and bearing meansdisposed between said ends of said longitudinally extending elongatedsupport members and said first and second means for accepting ends ofsaid longitudinally extending elongated support members, said bearingmeans comprising a bearing substrate and an upper bearing portiondisposed on said bearing substrate, said upper bearing portion includingconcavely curved side walls.

According to certain embodiments, the bearing includes an upper bearingportion having curved side walls, a substantially curved upper bearingsurface, and a flat seat region.

In another embodiment, an expansion joint system is provided for aroadway construction wherein a gap is defined between adjacent first andsecond roadway sections, said expansion joint system extending acrosssaid gap to permit vehicular traffic, said expansion joint systemcomprising transversely extending, spaced-apart, vehicular load bearingmembers, elongated support members having opposite ends positioned belowsaid transversely extending load bearing members and extendinglongitudinally across said expansion joint, means for movably engagingsaid longitudinally extending, elongated support members with at leastone of said transversely extending, spaced-apart load bearing members,and bearing means disposed between lateral sides of said longitudinallyextending elongated support members and surfaces of said means formovably engaging at least one of said longitudinally extending,elongated support members with said transversely extending, spaced-apartload bearing members, said bearing means comprising a bearing substrateand an upper bearing portion disposed on said bearing substrate, saidupper bearing portion including concavely curved side walls.

According to certain embodiments, the bearing includes an upper bearingportion having curved side walls, a substantially curved upper bearingsurface, and a flat seat region.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an exploded perspective view of the bearing structure.

FIG. 2 is a side view of the bearing structure in an uncompressed statein the absence of a load.

FIG. 3 is a side view of the bearing structure in a compressed state inresponse to the application of a load to the bearing.

FIG. 4 shows a top perspective view of the expansion joint systemincluding the bearing structure

FIG. 5 is a side view of an illustrative support bar member.

FIG. 6 is a rear view of the means for permitting transverse movement ofthe support bar members.

FIG. 7 is a side view of an illustrative support bar member insertedinto means for permitting transverse movement of the support bar member.

FIG. 8A is a side view of the means for permitting longitudinal andvertical movement of the support bar member.

FIG. 8B is an end view of the means for permitting longitudinal andvertical movement of the support bar member.

FIG. 9A is a side view of a portion of the expansion joint systemincluding an end view of the yoke assembly for maintaining the supportbar member in proximity to the bottom surfaces of the load bearing beamsof the expansion joint system.

FIG. 9B is an enlarged fragmentary side view of a portion of theexpansion joint system including an end view of the yoke assembly formaintaining the support bar member in proximity to the bottom surfacesof the load bearing beams of the expansion joint system.

DETAILED DESCRIPTION

An improved bearing structure is provided. Without limitation, thebearing can be utilized in connection with an expansion joint system inroadway constructions, bridge constructions, tunnel constructions, andother constructions where gaps are formed between spaced-apart, adjacentconcrete sections. The expansion joint system may be utilized where itis desirable to absorb loads applied to the expansion joint systems, andto accommodate movements that occur in the vicinity of the expansionjoint gap in response to the application of the applied loads to theexpansion joint system.

The bearing structure includes a bearing substrate and an upper bearingportion that is disposed on, or otherwise fitted over, a portion of thebearing substrate. The upper bearing portion of the bearing includescurved side walls and a curved upper bearing surface.

The bearing structure will now be described in greater detail withreference to the FIGURES. It should be noted that the bearing structureis not intended to be limited to the illustrative embodiments shown inthe FIGURES.

FIG. 1 shows an exploded side view of one embodiment of the bearingstructure 10. Bearing structure 10 comprises a substrate 11 that ismanufactured from a resilient material. According to the embodimentshown in FIG. 1, bearing substrate 11 is shown having a substantiallycylindrical shape. The bearing substrate 11 includes a top surface 12,bottom surface 13, and side walls 14 that extend between top surface 12and bottom surface 13.

Bearing structure 10 also includes an upper bearing portion 15. Upperbearing portion 15 includes a top bearing surface 16 and side walls 17extending downwardly away from top bearing surface 16. The side walls 17of upper bearing portion 15 include oppositely facing inner 18 and outer19 surfaces. The top bearing surface 16 and curved side walls 17,together, form a cap-like structure having an inner volume 20.

Now turning to FIG. 2, the bearing structure 10 is shown with upperbearing portion 15 engaged with the bearing substrate 11. Upper bearingportion 15 is engaged with bearing substrate 11 by disposing orotherwise fitting upper bearing portion 15 over a portion of bearingsubstrate 11. The upper bearing portion 15 is fitted over the topsurface 12 of bearing substrate 11, and the side walls 17 of upperbearing portion 15 extend over a portion of the side walls 14 of thebearing substrate 11.

According to FIG. 2, the bearing structure 10 is shown under conditionswhere no force or load is applied to the top bearing surface 16 of theupper bearing portion 15 of the bearing 10. The side walls 17 of theupper bearing portion 15 are constructed such that in the absence of aforce or load on the upper bearing portion 15 the sides walls 17 ofupper bearing portion 15 have a curved shape. That is, the side walls 17of upper bearing portion 15 remain concavely curved and “bow in” towardthe center of the upper bearing portion 15. A portion of the upperbearing surface 16 includes a flat seat region. The flat seat region ofupper bearing surface 16 may be centrally located.

Turning to FIG. 3, the bearing structure 10 is shown under conditionswhere a force or load (F) is applied to the top bearing surface 16 ofthe upper bearing portion 15. Under conditions where a force or load isapplied to the upper bearing surface 16 of the bearing 10, the sidewalls 17 of upper bearing portion 16 are urged downwardly along theouter surfaces of side walls 14 of bearing substrate 11 and upperbearing portion 16 moves into closer proximity with bearing substrate11. As upper bearing portion 15 is urged in a downward direction towardbearing substrate 11, the shape of the side walls 17 of upper bearingportion 15 undergo a transition from being concavely curved toward thecenter of the upper bearing portion 15 to a vertical configuration. Thatis, as top bearing portion 15 is urged downwardly the side walls 17change configuration from the concavely shaped side walls to a positionthat is perpendicular to the upper bearing surface 16 of upper bearingportion 15 and top surface 12 of bearing substrate 11. When an out oflevel force or load is applied to upper bearing surface 16 at an angle,the upper bearing portion 15 of structural bearing 10 is able totransmit the vertical load such that the bottom surface of the bearing“feels” very minimal eccentricity.

Distortional stresses in response to the application of a load to atraditional bearing structure often caused damage to the bearingstructure. The use of the bearing structure 10 having concavely curvedside walls 17 minimizes the distortional stresses below the bearingsurface in response to the application of a force or load. The optimizedgeometric combination of curved side walls, curved top bearing surface,and flat seat region reduces local distortional stresses directly belowthe applied load, and moves the maximum distortional stress region tobelow the surface, based on the accepted principles of elasticity.

It is known that prior art bearing structure stiffness remains nearlyconstant over the range of applications, as they are compressed inresponse to the application of a load to the bearing. The use of thebearing structure 10 having an upper bearing portion 15 with concavelycurved side walls 17 provides an increasing force versus deflectionspring rate. Utilizing the bearing structure 10 having an upper bearingportion 15 with curved side walls 17 permits the bearing structure to beprecompressed to a significant degree, thereby mitigating bearingvibration when large vehicular impact loads are applied to the bearing.Additionally, the use of the bearing structure 10 having an upperbearing portion 15 with curved side walls 17 stabilizes largedisplacements in response to loads applied to the bearing 10.

In general, the top bearing surfaces of prior art bearings expand andcontract against the support bar of the expansion joint systems inresponse to an application of a load, which causes significant rubbingand friction between the top bearing surfaces of the bearings and thesurfaces of the support bar of the expansion joint systems. In contrast,upper bearing portion 15 of the bearing structure 10 expands upward tocontact the surface of the support bar of the expansion joint systems.Under these conditions, less surface rubbing and friction occur betweenthe top bearing surface 16 and the surface of the support bars of theexpansion joint system. Because there is less friction between the topbearing surface 16 of the bearing 10 and the surfaces of the supportbars, there is a significant decrease in the surface wear of the bearing10. Thus, the overall life of the bearing is increased.

The side walls of the prior art bearings bulge outwardly upon anapplication of a load to the top bearing surface. These bearings,sometimes referred to as parabolic bulge bearings, are bonded on the topand bottom surfaces, and are free to bulge on their sides. Thesebearings produce very large surface shears at the point where the freeedge of the bearing meets the bonded surfaces. In contrast to prior artparabolic bulge bearings, the side walls 17 of bearing 10 areconstructed in such a manner that upon maximum compression by a loadapplied to the bearing, the side walls 17 of upper bearing portion 15are vertical. This is a significant improvement over prior art parabolicbulge bearings, as shear strains at the point of the bond of the freeedge to the bonded edge is minimized.

An expansion joint system incorporating the improved structural bearing10 is further provided. The expansion joint system may be utilized in aroadway construction wherein a gap is defined between adjacent first andsecond roadway sections. The expansion joint system extends across thegap between adjacent concrete roadway sections to permit vehiculartraffic. The expansion joint system comprises transversely extending,spaced-apart, vehicular load bearing members. Elongated support membershaving opposite ends are positioned below the transversely extendingload bearing members and extend longitudinally across the gap in theexpansion joint from a first concrete roadway section to a secondconcrete roadway section. According to certain embodiments, theexpansion joint system also includes first means for accepting firstends of the longitudinally extending elongated support members forcontrolling the movement of the ends of the support members within thefirst means for accepting longitudinally extending elongated supportmembers, and second means for accepting opposite ends of thelongitudinally extending elongated support members for controlling themovement of the opposite ends of said support members within the secondmeans for accepting longitudinally extending elongated support members.Bearing structures 10 are disposed between sides surfaces of theopposite first and second ends of the longitudinally extending elongatedsupport members and inner surfaces of the first and second means foraccepting ends of the longitudinally extending elongated support membersto absorb loads applied to the expansion joint system. The bearingstructure includes a substrate and an upper bearing portion that isdisposed on, or otherwise fitted over, the substrate. The upper bearingportion of the bearing comprises curved side walls and a curved upperbearing surface.

According to other embodiments, the expansion joint system includestransversely extending, spaced-apart, vehicular load bearing members,elongated support members having opposite ends positioned below thetransversely extending load bearing members and extending longitudinallyacross the expansion joint, and means for movably engaging thelongitudinally extending, elongated support members with thetransversely extending, spaced-apart load bearing members. Bearings 10are disposed between surfaces of lateral sides of the longitudinallyextending elongated support bar members and surfaces of the means formovably engaging the longitudinally extending, elongated support barmembers with the transversely extending, spaced-apart load bearingmembers. The bearing structure 10 includes a substrate and an upperbearing portion that is disposed on, or otherwise fitted over, thesubstrate. The upper bearing portion of the bearing comprises curvedside walls and a curved upper bearing surface.

Now referring to illustrative FIG. 4, expansion joint system 30 includesa plurality of vehicular load bearing members 31-37. The vehicular loadbearing members 31-37 of expansion joint system 30 are positioned in thegap between the adjacent roadway sections (not shown). The vehicle loadbearing members are often referred to in the art as “center beams.”While illustrative FIG. 4 shows seven transversely extending loadbearing members 31-37, it should be noted that the expansion jointsystem 30 may include any number of transversely extending load bearingmembers, depending on the size of the gap of the particularconstruction. According to certain embodiments, the load bearing membershave a generally square or rectangular cross section. Nevertheless, theload bearing members 31-37 are not limited to members havingapproximately square or rectangular cross sections, but, rather, theload bearing beam members 31-37 may comprise any number of crosssectional configurations or shapes. The shape of the cross section ofload bearing beam members 31-37 is only limited in that the load bearingbeams 31-37 must be capable of permitting relatively smooth andunimpeded vehicular traffic across the top surfaces of the load bearingbeam members, and the load bearing beam members must have the ability tosupport engaging means that are engaged to the bottom surfaces of theload bearing beam members to engage the longitudinally extendingelongated support members. According to certain embodiments, the topsurfaces of the load bearing beam members may, for example, also becontoured to facilitate the removal of debris and liquids, such asrainwater runoff.

The load bearing beam members 31-37 are positioned in a spaced apart,side-by-side relationship and extend transversely in the expansion jointgap relative to the direction of vehicle travel. That is, the loadbearing members 31-37 extend substantially perpendicular, relative tothe direction of vehicle travel across the expansion joint system 30.The top surfaces of the load bearing beam members are adapted to supportvehicle tires as a vehicle passes over the expansion joint. Compressibleseals (not shown in FIG. 1, but shown in FIG. 9) may be placed andextend transversely between the positioned vehicular load bearing beammembers 31-37 adjacent the top surfaces of the beam members 31-37 tofill the spaces between the beam members 31-37. The seals may also beplaced and extend in the space between end beam member 31 and edge plate38 and to extend between end beam member 37 and edge plate 39. The sealsare flexible and compressible and, therefore, can stretch and contractin response to movement of the load bearing beams within the expansionjoint. The seals are preferably made from a durable and abrasionresistant elastomeric material. The seal members are not limited to anyparticular type of seal. Suitable sealing members that can be usedinclude, but are not limited to, strip seals, glandular seals, andmembrane seals.

Still referring to FIG. 4, the expansion joint system 30 includeselongated support bar members 40-43. Support bar members 40-43 arepositioned in a spaced-apart, side-by-side relationship and extendlongitudinally across the gap of the expansion joint, relative to thedirection of the flow of vehicular traffic. That is, the support barmembers 40-43 extend substantially parallel relative to the direction ofvehicle travel across the expansion joint system 30. The support barmembers 40-43 provide support to the vehicle load bearing beams 31-37 asvehicular traffic passes over the expansion joint system 30. Support barmembers 40-43 also accommodate transverse, longitudinal and verticalmovement of the expansion joint system 30 within the gap.

Opposite ends of the support bar members 40-43 are received intosuitable means for accepting the ends of the support bar members, andseveral means for accepting the support bar members are disposed, orembedded in portions of respective adjacent roadway sections in theroadway construction. The expansion joint system 30 can be affixedwithin the “block-out” areas between two adjacent roadway sections bydisposing the system 30 into the gap between the roadway sections andpouring concrete into the block-out portions or by mechanically affixingthe expansion joint system 30 in the gap to underlying structuralsupport. Mechanical attachment may be accomplished, for example, bybolting or welding the expansion joint system 30 to the underlyingstructural support.

In accordance with the invention, provision is made for particular typesof movement of the support bar members 40-43 within the separate meansfor accepting the ends of the support bar members. In one embodiment,the means for accepting the ends of the support bar members comprisebox-like structures. It should be noted, however, that the means foraccepting the ends of the support bar members may include any structuresuch as, for example, receptacles, chambers, housings, containers,enclosures, channels, tracks, slots, grooves or passages, that includesa suitable cavity for accepting opposite end portions of the support barmembers 40-43.

Still referring to FIG. 4, the expansion joint system 30 includes firstmeans 50 for confining the first ends of the support bars 40-43 againstlongitudinal movement within the first means 50 for accepting, butpermitting transverse movement of the first ends within the first means50 for accepting. Therefore, the expansion joint system 30 includesfirst means for accepting first ends of the longitudinally extendingelongated support members which include means for substantiallyrestricting longitudinal movement within the first means for accepting,but permitting transverse and vertical movement within said first meansfor accepting.

The expansion joint system 30 includes second means 51 for acceptingopposite ends of the support members 40-43 for confining the oppositeends of the support bars 40-43 against transverse movement within thesecond means 51 for accepting, but permitting longitudinal movement andvertical movement within the second means 51 for accepting. Therefore,the expansion joint system 30 includes second means for accepting endsof said longitudinally extending elongated support members whichincludes means for substantially restricting transverse movement withinsaid second means for accepting, but permitting longitudinal movementwithin said second means for accepting.

FIG. 5 shows an illustrative support member 60 of the expansion jointsystem 30. The support member 60 is shown as an elongated bar-likemember having a square cross section. It should be noted, however, thatthe support member 60 is not limited to elongated bar members havingsquare cross sections, but, rather, the support member 60 may comprisean elongated bar member having a number of different cross sectionalshapes such as, for example, round, oval, oblong and rectangular. Thesupport bar 60 includes opposite ends 61, 62. Illustrative support bar60 includes a hole 63 communicating from one side 64 of the support bar60 to the other side 65. According to this embodiment, the hole 63 isadapted to receive a securing means. End 62 of the support bar 60 havingthe hole 63 therein is adapted to be inserted into first means 50 forpermitting transverse and vertical movement, but substantiallyrestricting longitudinal movement of the support member 60 of theexpansion joint system 30 within the means 50.

FIG. 6 shows a side view of means 50, which according to the embodimentshown is a substantially rectangular box structure, and which permitstransverse and vertical movement of support bars 40-43 of the expansionjoint system 30 in response to movement within the expansion joint. Thetransverse and vertical movement box 50 includes top 52 and bottom 53plates, side plates 54, 55 and back plate (not shown). According to thisembodiment, the securing means 56 is an elongated, substantiallycylindrical guide rod to which a support bar 40-43 is engaged. Thesecuring means 56 is substantially centrally disposed within box 50 mayextend across box 50 from side plate 54 to side plate 55. The securingmeans 56 may be held in place by holding plates 57, 58, which areattached to the inside wall surfaces 59 a, 59 b of side plate 54 andside plate 55, respectively. The securing means 56 is inserted into thehole 63 in order to secure the support bar 40-43 within means 50. Thesecurement means 56 can be any means which permits pivotable movement ofend 62 of the support bar in the vertical direction within means 50,while further permitting transverse movement of end 62 of the supportbar along the axis of the securement means. Thus, the securing means 56substantially restricts longitudinal movement of the support bars 40-43,but permits transverse and vertical movement. While the securing means56 is shown in FIG. 6 as a cylindrical guide rod, it may, for example,include differently shaped rods, bars, pegs, pins, bolts, and the like.

FIG. 7 shows one end 62 of the support bar 60 inserted into means 50.Bearing means 10 are disposed between the top surface of support barmember 60 and the inner surface 52 a of top plate 52 of box 50 andbetween the bottom surface of the support bar member 60 and the innersurface 53 a of bottom plate 53. The rigid bearing substrate 11 ofbearing structure is positioned adjacent to inside surface 52 a of topplate 52 and top bearing surface 16 of upper bearing portion 15 maycontact top surface of support bar member 60. A second bearing means 10is positioned within box 50. The rigid bearing substrate 11 of thesecond bearing structure is positioned adjacent to inside surface 53 aof bottom plate 53 and top bearing surface 16 of upper bearing portion15 may contact bottom surface 64 of support bar member 60.

FIGS. 8A and 8B shows longitudinal movement support box 51. Box 51includes means for permitting longitudinal and vertical movement of thesupport bars 40-43 within box 51, and means for substantially preventingtransverse movement of support bars 40-43 within the box 51. Preferably,the upper 71 and lower 72 bearing means maintain the vertical load onthe support bars perpendicular to the axis of the support bars and,permits slidable movement of the support bars in the direction ofvehicular traffic flow (longitudinal movement). Upper and lower bearingmeans 71,72 are the constructed like bearing structure 10 described inFIGS. 1-3. As shown in FIG. 8B, side bearing means 73, 74 substantiallyprevent transverse movement of support bars 40-43 within box 51, whilenot inhibiting or otherwise preventing longitudinal and verticalmovement. According to the embodiment shown, side bearing means 73, 74are provided in the form of bearing plates that are disposed adjacentthe inner surfaces of box 51.

The use of the upper 71 and lower 72 bearings maintain the vertical loadon the bearings perpendicular to the sliding surfaces. The upper andlower bearings are capable of absorbing impact from vehicular trafficmoving across the expansion joint system.

The transverse movement box for receiving one end of the support bars isdesigned to permit transverse and vertical movement of the support barswithin the boxes in response to changes in temperature changes, seismicmovement or deflections caused by vehicular traffic, while restrictinglongitudinal movement. Longitudinal boxes for receiving the oppositeends of the support bars are designed to permit relative longitudinaland vertical movement of the support bar within the boxes, whileconfining the bars against relative transverse movement.

Means are provided to maintain the position of support bars 40-43relative to the bottom surfaces of the load bearing beams members 31-37.Also, the means permit longitudinal and limited vertical movement of thesupport bars 40-43 within the means. FIGS. 9A and 9B show one embodimentof the means, which comprises a yoke or stirrup assembly 80 forretaining the position of the support bars 40-43 relative to the bottomsurfaces of the load bearing beams 31-37 of the expansion joint system30. As shown in FIG. 9B, the yoke assembly 80 includes spaced-apart yokeside plates 81, 82 that are attached to and extend away from the bottomsurface of the vehicular load bearing beam 31. Bent yoke plate 83includes leg portions 84, 85 and spanning portion 86 that extendsbetween legs 84, 85. The yoke assembly 80 also includes upper yokebearing 87 and lower yoke bearing 88. The yoke assembly 80 utilizesupper 87 and lower 88 yoke bearings to minimize yoke tilt and optimizesthe ability of the expansion joint system 30 to absorb vehicular impactfrom traffic moving across the expansion joint system 30. While the oneembodiment is shown utilizing a yoke or stirrup assembly to maintain thepositioning of the support bars 40-43, any restraining device or thelike that can maintain the position of the support bars 40-43 relativeto the load bearing beams 31-37 may be utilized.

Yoke assembly 80 may further include yoke retaining rings 90, 91 andyoke discs 92, 93, which are located on the inner surfaces of bent yokelegs 74, 75. The yoke retaining rings 81, 82 and yoke discs 83, 84 areprovided to allow limited vertical and longitudinal movement of thesupport bars 40-43. Furthermore, the yoke side plates 81, 82 are spacedapart at a distance sufficient to permit bent yoke plate 83 to beinserted in the space defined by the inner surfaces of yoke side plates81, 82.

The expansion joint system 30 may also include means for controlling thespacing between the transversely extending load bearing beam members31-37 in response to movement in the vicinity of the expansion joint. Inone embodiment, the means for controlling the spacing between beammembers 31-37 maintains a substantially equal distance between thespaced-apart, traffic load bearing beams 31-37 that are transverselypositioned within the gap in an expansion joint, in response tomovements caused by thermal or seismic cycling and vehicle deflections.

The expansion joint system of the invention is used in the gap betweenadjacent concrete roadway sections. The concrete is typically pouredinto the blockout portions of adjacent roadway sections. The gap isprovided between first and second roadway sections to accommodateexpansion and contraction due to thermal fluctuations and seismiccycling. The expansion joint system can be affixed within the block-outportions between two roadway sections by disposing the system into thegap between the roadway sections and pouring concrete into the block-outportions or by mechanically affixing the expansion joint system in thegap to underlying structural support. Mechanical attachment may beaccomplished, for example, by bolting or welding the expansion jointsystem to the underlying structural support.

While the present invention has been described above in connection withthe preferred embodiments, as shown in the various figures, it is to beunderstood that other similar embodiments may be used or modificationsand additions may be made to the described embodiments for performingthe same function of the present invention without deviating therefrom.Further, all embodiments disclosed are not necessarily in thealternative, as various embodiments of the invention may be combined toprovide the desired characteristics. Variations can be made by onehaving ordinary skill in the art without departing from the spirit andscope of the invention. Therefore, the present invention should not belimited to any single embodiment, but rather construed in breadth andscope in accordance with the recitation of the attached claims.

1. A bearing comprising: a bearing substrate; and an upper bearingportion disposed on said bearing substrate, said upper bearing portionincluding curved side walls and a curved upper bearing surface,concavely curved side walls and a flat seat region.
 2. The bearing ofclaim 1, wherein said upper bearing portion further comprises a curvedupper bearing surface with a flat seat region.
 3. The bearing of claim1, wherein said curved side walls of said upper bearing portion areconcavely curved toward the center of said upper bearing portion.
 4. Thebearing of claim 1, wherein said bearing substrate is substantiallycylindrical.
 5. The bearing of claim 1, wherein said side walls of saidupper bearing portion are bonded over at least a portion of said bearingsubstrate.
 6. The bearing of claim 1, wherein said substrate comprises amaterial that substantially resists a conformational change in responseto the application of a load.
 7. The bearing of claim 1, wherein saidupper bearing portion comprises a material that is capable of undergoinga conformational change in response to the application of a load to saidbearing.
 8. The bearing of claim 7, wherein said upper bearing portionis capable of undergoing a conformational change in response to theapplication of a maximum load to said bearing, whereby said side wallsof said upper bearing portion change conformation from being concavelycurved to a conformation that is substantially perpendicular to saidupper surface of said bearing substrate of said bearing.
 9. The bearingof claim 1, wherein said substrate comprises a material selected fromthe group consisting of polymers, composites, and metal alloys.
 10. Thebearing of claim 9, wherein said composite comprises a fiber reinforcedpolymer.
 11. The bearing of claim 9, wherein said polymer is selectedfrom the group consisting of urethane, polytetrafluoroethylene,polyethylene, phenolic, and nylon polymers.
 12. The bearing of claim 11,wherein said polymer is a phenolic polymer.
 13. The bearing of claim 9,wherein said metal alloy is selected from the group consisting of bronzeand steel.
 14. The bearing of claim 1, wherein said upper bearingportion comprises an elastomeric material.
 15. The bearing of claim 14,wherein said elastomeric material is selected from the group consistingof polyurethane, polychloroprene, isoprene, styrene butadiene rubber,and natural rubber.
 16. The bearing of claim 15, wherein saidelastomeric material is a urethane material.
 17. An expansion jointsystem for roadway construction wherein a gap is defined betweenadjacent first and second roadway sections, said expansion joint systemextending across said gap to permit vehicular traffic, said expansionjoint system comprising: transversely extending, spaced-apart, vehicularload bearing members; elongated support members having opposite endspositioned below said transversely extending load bearing members andextending longitudinally across said expansion joint; first means foraccepting ends of said longitudinally extending elongated supportmembers for controlling the movement of said ends of said supportmembers within said first means for accepting longitudinally extendingelongated support members; second means for accepting opposite ends ofsaid longitudinally extending elongated support members for controllingthe movement of said opposite ends of said support members within saidsecond means for accepting longitudinally extending elongated supportmembers; and bearing means disposed between surfaces of saidlongitudinally extending elongated support members and inner surfaces ofat least one of said first and second means for accepting ends of saidlongitudinally extending elongated support members, said bearing meanscomprising a bearing substrate and an upper bearing portion disposed onsaid bearing substrate, said upper bearing portion including concavelycurved side walls.
 18. The expansion joint system of claim 17, whereinsaid upper bearing portion further comprises a curved upper bearingsurface with a flat seat region.
 19. The expansion joint system of claim17, further comprising means for controlling the spacing of saidtransversely extending, spaced-apart, load bearing members relative toone another.
 20. The expansion joint system of claim 17, wherein saidlongitudinally extending load bearing members extend across saidexpansion joint gap from said first roadway section to said secondroadway section.
 21. The expansion joint system of claim 17, whereinsaid first and second means for accepting said ends of saidlongitudinally extending elongated support members are structuresselected from the group consisting of boxes, receptacles, chambers,housings, containers, enclosures, channels, tracks, slots, grooves, andpassages.
 22. The expansion joint system of claim 17, wherein said firstmeans for accepting said opposite ends of said longitudinally extendingelongated support members substantially restricts longitudinal movementof said longitudinally extending elongated support members within saidfirst means for accepting, but permits transverse and vertical movementof said longitudinally extending elongated support members within saidfirst means for accepting; and wherein said second means for acceptingends of said longitudinally extending elongated support memberssubstantially restricts transverse movement of said longitudinallyextending elongated support members within said second means foraccepting, but permits longitudinal movement of said longitudinallyextending elongated support members within said second means foraccepting.
 23. The expansion joint system of claim 17, furthercomprising means for movably engaging said longitudinally extending,elongated support members with said transversely extending, spaced-apartload bearing members.
 24. The expansion joint system of claim 23,wherein said means for movably engaging said longitudinally extending,elongated support members with said transversely extending, spaced-apartload bearing members comprises a yoke assembly.
 25. The expansion jointsystem of claim 24, wherein said yoke assembly comprises spaced-apartyoke side plates and a bent yoke plate spanning the gap between saidspaced-apart yoke side plates.
 26. The expansion joint system of claim25, wherein said yoke assembly slidably engages said longitudinallyextending, elongated support members with at least one of saidtransversely extending, spaced-apart load bearing members.
 27. Theexpansion joint system of claim 17, wherein said curved side walls ofsaid upper bearing portion are concavely curved toward the center ofsaid upper bearing portion.
 28. The expansion joint system of claim 17,wherein said bearing substrate is substantially cylindrical.
 29. Theexpansion joint system of claim 17, wherein said side walls of saidupper bearing portion are bonded over at least a portion of said bearingsubstrate.
 30. The expansion joint system of claim 17, wherein saidsubstrate comprises a material that substantially resists aconformational change in response to the application of a load.
 31. Theexpansion joint system of claim 17, wherein said upper bearing portioncomprises a material that is capable of undergoing a conformationalchange in response to the application of a load to said bearing.
 32. Theexpansion joint systems of claim 31, wherein said upper bearing portionis capable of undergoing a conformational change in response to theapplication of a maximum load to said bearing, whereby said side wallsof said upper bearing portion change conformation from being concavelycurved to a conformation that is substantially perpendicular to saidupper surface of said upper bearing portion of said bearing.
 33. Theexpansion joint system of claim 17, wherein said substrate comprises amaterial selected from the group consisting of polymers, composites, andmetal alloys.
 34. The expansion joint system of claim 33, wherein saidcomposite material comprises fiber reinforced polymers.
 35. Theexpansion joint system of claim 33, wherein said polymer is a polymerselected from the group consisting of urethane, polytetrafluoroethylene,polyethylene, phenolic, and nylon polymers.
 36. The expansion jointsystem of claim 35, wherein said polymer is a phenolic polymer.
 37. Theexpansion joint system of claim 33, wherein said metal alloy is selectedfrom the group consisting of bronze and steel.
 38. The expansion jointsystem of claim 17, wherein said upper bearing portion comprises anelastomeric material.
 39. The expansion joint system of claim 38,wherein said elastomeric material is selected from the group consistingof polyurethane, polychloroprene, isoprene, styrene butadiene rubber,and natural rubber.
 40. The expansion joint system of claim 39, whereinsaid elastomeric material is a polyurethane material.
 41. The expansionjoint system of claim 17, comprising seals extending between saidtransversely extending, spaced-apart load bearing members.
 42. Theexpansion joint system of claim 17, comprising seals extending betweensaid transversely extending, spaced apart load bearing members, andbetween said transversely extending, spaced apart load bearing membersand edge sections of said first and said second roadway sections. 43.The expansion joint system of claim 42, wherein said seals are flexibleand compressible.
 44. The expansion joint system of claim 42, whereinsaid seals comprise an elastomeric material.
 45. The expansion jointsystem of claim 44, wherein said seals are selected from strip seals,glandular seals, and membrane seals.
 46. The expansion joint system ofclaim 45, wherein said seals are strip seals.
 47. An expansion jointsystem for roadway construction wherein a gap is defined betweenadjacent first and second roadway sections, said expansion joint systemextending across said gap to permit vehicular traffic, said expansionjoint system comprising: transversely extending, spaced-apart, vehicularload bearing members; elongated support members having opposite endspositioned below said transversely extending load bearing members andextending longitudinally across said expansion joint; means for movablyengaging said longitudinally extending, elongated support members withat least one of said transversely extending, spaced-apart load bearingmembers; and bearing means disposed between surfaces of saidlongitudinally extending elongated support members and surfaces of saidmeans for movably engaging at least one of said longitudinallyextending, elongated support members with said transversely extending,spaced-apart load bearing members, said bearing means comprising abearing substrate and an upper bearing portion disposed on at least aportion of said bearing substrate, said upper bearing portion includingconcavely curved side walls.
 48. The expansion joint system of claim 47,wherein said upper bearing portion further comprises a curved upperbearing surface with a flat seat region.
 49. The expansion joint systemof claim 47, wherein said curved side walls of said upper bearingportion are concavely curved toward the center of said upper bearingportion.
 50. The expansion joint system of claim 47, wherein saidbearing substrate is substantially cylindrical.
 51. The expansion jointsystem of claim 47, wherein said side walls of said upper bearingportion are bonded over at least a portion said bearing substrate. 52.The expansion joint system of claim 47, wherein said substrate comprisesa material that substantially resists a conformational change inresponse to the application of a load.
 53. The expansion joint system ofclaim 47, wherein said upper bearing portion comprises a material thatis capable of undergoing a conformational change in response to theapplication of a load to said bearing.
 54. The expansion joint system ofclaim 53, wherein said upper bearing portion is capable of undergoing aconformational change in response to the application of a maximum loadto said bearing, whereby said side walls of said upper bearing portionchange conformation from being concavely curved to a conformation thatis substantially perpendicular to said upper surface of said upperbearing portion of said bearing.
 55. The expansion joint system of claim47, wherein said bearing substrate comprises a material selected fromthe group consisting of polymers, composites, and metal alloys.
 56. Theexpansion joint system of claim 55, wherein said composite materialcomprises fiber reinforced polymers.
 57. The expansion joint system ofclaim 55, wherein said polymer is selected from the group consisting ofurethane, polytetrafluoroethylene, polyethylene, phenolic, and nylonpolymers.
 58. The expansion joint system of claim 57, wherein saidpolymer is a phenolic polymer.
 59. The expansion joint system of claim55, wherein said metal alloy is selected from the group consisting ofbronze and steel.
 60. The expansion joint system of claim 47, whereinsaid upper bearing portion comprises an elastomeric material.
 61. Theexpansion joint system of claim 60, wherein said elastomeric material isselected from the group consisting of polyurethane, polychloroprene,isoprene, styrene butadiene rubber, and natural rubber.
 62. Theexpansion joint system of claim 61, wherein said elastomeric material isa polyurethane material.
 63. The expansion joint system of claim 47,further comprising means for controlling the spacing of saidtransversely extending, spaced-apart, load bearing members relative toone another.
 64. The expansion joint system of claim 47, wherein saidmeans for movably engaging said longitudinally extending, elongatedsupport members with at least one of said transversely extending,spaced-apart load bearing members comprises a yoke assembly.
 65. Theexpansion joint system of claim 47, comprising seals extending betweensaid transversely extending, spaced-apart load bearing members.
 66. Theexpansion joint system of claim 47, comprising seals extending betweensaid transversely extending, spaced apart load bearing members, andbetween said transversely extending, spaced apart load bearing membersand edge sections of said first and said second roadway sections. 67.The expansion joint system of claim 66, wherein said seals are selectedfrom the group consisting of glandular seals, membrane seals, and stripseals.